Pump



March 14, 1933.

ojs. sLEE-PE'R PUMP Filed OOC. 20, 1930 2 Sheets-Sheet l y March 14, 1933. o. s. SLEEPER PUMP Filed OCL. 20, 1930 2 Sheets-Sheet 2 p67 M Mx kwar- Patented Mar. 14, 1933 UNITED STATES PATENT ori-ICE OLIVER S. SLEEPER, F MOUNT VERNON, ILLINOIS, ASSIGNOR T0 J'. P. DEVINE MANU- FACTURIN G COMPANY, OF MOUNT VERNON, ILLINOIS, CORPORATION OF ILLINOIS PUMP Application mea october 2o, 1930. serial No. 489,817.

My invention relates to vacuum pumps, and includes among its ob]ects and advantages a better seal between the moving parts whereby higher vacuums may be obtained,

accompanied at the same time .by an 1ncrease in simplicity of construction and in durability.

Referring to the drawings:

Fig. l1 is a vertical transverse section of a l0 pump according to the invent1on;

Fig. 2 is a central vertical longitudinal section of the same pump; n

Fig. 3 is a perspective view of the piston and the associated movable parts for sealing the intake.

In the embodiment selected to illustrate the invention, the hollow base 10 is provlded with lugs 12 to fasten it in place, and has an opemng 14 covered by the pump casting 16. The lower edge 18 of the outer wall of the pump casting has an outwardly extending flange 2O bolted to the base l0 by the cap screws 22, and an inwardly extendlng flange supporting a bottom plate 24.

25 The piston 26 moves in the cylinder 28 in a circular path about the center of the shaft in such a way that the periphery of the piston always has line contact with the outer wall of the cylinder except ad- 30 jacent the position of Fig. 1, where the cylinder wall is interrupted by the bore 32. This movement isproduced by an eccentric ..34 carried by the shaft 30 and rotating inside the piston 26.

The bore 32 communicates with an intake chamber 36 located above it, and the intake to the cylinder is sealed by an extension or slide 38 integral with the piston 26 and extending upward through the bore 32 into 40 the inlet chamber 36, being guided between two segmental guide blocks 40 and 42. The guide blocks have flat faces sliding on the flat sides ofthe extension 38 and cylindrical faces having sliding engagement with the bore 32.

The inlet 39 to the cylinder is an opening running down through the extension 38 to port means 44 in the nature of a series of lateral openings through one side face of the extension. These port means in the position of Fig. 1 are covered and sealed by the right hand guide block 42 land will remain so until the eccentric has moved in a clockwise direction from the position of Fig. l for a considerable distance, and the line contact between the piston and cylf inder has been established and is moving downward along the right side of the cylinder. Then the ports 44 will be uncovered and the enlargement of the cylinder space with which they communicate will suck the material out of the intake chamber 36 into the cylinder. At the same time the contraction of the cylinder space in front of the contact between the piston and the cyl- 65 inder will sweep the' contents of that space up the left side of the cylinder out through the discharge ports 46 controlled by a flap valve 48. This flap valve is a thin steel member provided with a guard 52 to limit the movement of the flap valve away from the exhaust ports. The guard 52 and valve 48 are bolted to the casting 16 by bolts 50. A removable cover 54 overlies the chamber 56 housing the discharge valve. From the chamber 56 the gases move downwardly through a passage 58 and are deflected by a lip 60 cast on the end of the bottom plate 24 over to the left end of the base 10. They may then pass to the right end of the base l0 out to the atmosphere through an outlet at 62.

The drive shaft 30 is supported in spaced roller bearings 64 and 66, one supported in a housing integral with the left end plate 68 and the ot er set out on a spider orbracket 70. I have illustrated the shaft projecting beyond the right hand bearing 66 and carrylng a combined flywheel and pulley 72 by means of which the pump ma be driven. Where the shaft passes throng the right hand` end plate 74 I provide a leakage-resisting packing in the nature of a sleeve or bushing 76 followed by a yplurality of packing rings 78 held compressed 95 Y by a gland nut 80. At the other end of the shaft I provide a hermetic seal by means of a cover plate 82 bolted to the end of the housing 84 for the roller bearing 64 and covering the end of the drive shaft.

The eccentric 34, piston 26, piston ex-' tension 38, and segmental guide blocks 40 and 42, all have plane end faces and are all machined so that their end faces will all lie in the same plane. The cover plates 68 and 74 closing the ends of the cylinder 28, the bore 32, and the intake chamber 36, have smooth machined surfaces. Furthermore, all these parts are devoid of oil grooves of any sort, and the clearances between the parts, both axial and radial, are of the order of magnitude of 2/1000thsof an inch. The joints between the end plates and the cylinder casting are not sealed with gaskets, but the surface of the metal is shellacked to form a tight seal. This not only provides ka perfect seal, but positions the end plates with greater accuracy than would be possible ifa compressible gasket were employed.

The lubrication of the pump is performed in such a way as to accomplish complete sealing of the parts against leakage as well as lubrication in the ordinary sense of the word. A body of oil is kept in the hollow base l0 and may be drawn up through a conduit 86 by the vacuum or reduced pressure inside the pump. The conduit 86 branches into three conduits 88, 90, and 92. Of these the conduit 90 leads through a valve 94 into the housing for the left roller bearing 64. Another conduit 92 extends through a control valve' 96 and opens into the housing for the packing rings 78. The third conduit 88 extends up through a control valve 98 and opens through one of the end plates 68 at a point 99 that is transversed by the adjacent end face of the slide.

Sufficient oil is delivered through the system just described to maintain a film of oil between all surfaces having relative sliding movement. I prefer to have the left roller bearing get about enough oil to fill the same and maintain an oil film between the adjacent end faces of the eccentric and piston and the end plate. I prefer to deliver sufficient olil to the housing 100 to saturate the packing and work past the bushing 76 and maintain an oil film between the adjacent ends of the eccentric and piston and the end plate 74. With the parts properly machined, the oil supply specified will result if the valves 94 and 96 are left wide open.

I prefer to deliver enough oil yinto the intake chamber to maintain an oil seal above the exposed portions of the guide blocks 40 and 42 so that the film of oil sealing the opposed faces of the guide blocks and slide and the opposed faces of the guide blocks and the bore 32 will always be maintained. I also deliver oil to this chamber at a rate in excess of the absorption of oil by the films just mentioned, and by the corresponding films between the ends of the slide and guide blocks and the end plates. When the slide reaches the bottom of its stroke, its upper end moves down between the guide blocks so that the side faces of the guide will be completely transversed by the opposed faces of the blocks and kept smooth and polished throughout. Therefore, at the bottom point of the movement of the guide when the velocity of the gases entering the intake passage 39 is a maximum, a little oil Will get over into the passage 39 and will be forcibly drawn into the cylinder along with the air or gas being pumped. In this way a sufficient oil film is maintained over the inner surface of the cylinder and the outer surfaces of the piston to maintain an oil seal at'the line of contact between the cylinder and the piston.

By making the parts devoid of oil grooves and employing the minimum clearances conveniently possible in commercial manufacturing practice, I am able to have the oil films fed by the body of oil in the bottom of the intake chamber take so little oil that the transfer of oil to the cylinder proper through these films is materially less than the oil needed to lubricate the cylinder, so that the operator, by means of the valve 98, may control the amount of oil in the cylinder and adjust it to that at which the highest vacuum results.

By employing two separate and discon- 'nected guide blocks 40 and 42 I very materially decrease the possibility of leakage bac-k between the cylinder extension and either guide block. More particularly, toward the end of the stroke, when the compressed air about to find its way out through the discharge valve is at its highest pressure, the individual guide block 4U on the left of the extension and adjacent the exhaust port, will be moving in a counterclockwise direction, and its upper right hand' corner will be receiving thrust from the extension, so that ,if there should be an appreciable looseness or clearance vbetween the parts, there will still be a line of contact all across the faces between which air might get back. In previous constructions, the guide blocks on opposite sides have been part of the same rigid structure. Vith such a sealing means, the side thrust of the extension against the right hand guide block during the latter :part of he compression stroke would be timed just right to maintain an opening between the extension and the left hand guide block at a maximum, open and continuous all the way back to the intake chamber.

The oil in the base l0 is watercooled, and the pump casting is made with a water jacket completely encircling the cylinder throughoutmost of its length except for the relatively short axial extent of the air exit passage which terminates in a wall 102 best seen in Fig. 2.` The water may enter at 104 and pass through the cooling coils in the bottom of the base 10,\ and from there through a conduit 106 into the Water chamber 108 around the cylinder, and out at 110.

During the operation, more or less water may accumulate in the base, and this may gravitate into a sump 112 and be drawn off through an opening 114 provided with a petcock 116. I prefer to provide a high gauge glass 118 in which the level of the oil may be observed and a low gauge glass 120 in which the level of the water under the oil may be observed.

Without further elaboration, the foregoing will so fully explain my invent-ion that others may, by applying current knowledge, readily adapt the same for use under various conditions of service.

I claim:

1. A vacuum pump comprising a housing,

^ a drive shaft in said housing having a hermetically sealed bearing at one end and a packed bearing` at the other end, an eccentric cylinder on said drive shaft in sald housing, a blade integral with said cylinder and having an inlet passage leading down from the upper end thereof, sealing segments journaled in said housing and lying on either side of said blade, said housing definingan inlet chamber above said sealing segments, an oil reservoir subjected to the pressure on the discharge side of said pump', a branched conduit from said reservoir having a branch leading to each shaft bearing and a branch leading to said inlet chamber, individual oil flow control means in each branch, said blade and sealing segments fitting so closely to each other and to said housing that lubricant from said inlet chamber is not permitted to reach said bearings in sufficient quantities for proper lubrication, whereby manipulation of the oil control means in the branch leading to said inlet chamber may establish a bath for lubricating said segments and a controllable additional oil supply for said cylinder, all said moving parts having plane ends terminating in the same planes and having peripheral and end surfaces smooth and devoid of oil grooves, said housing being made up of a body portion with plane end faces, and end plates sealed against the body ,portion by shellacked joints. l

2. A vacuum pump comprising a housing, a drive shaft in said housing, an eccentric cylinder on said drive shaft in saidhousing, a blade integral with said cylinder and extending upwardly therefrom, sealing segments journaled in said housing 'and lying on either side of said blade, said housing defining an inlet chamber above said sealing segments, an oil reservoir subjected to.

the pressure on the discharge side of said pump', a branched conduit fnom said reservoir having a branch leading to each shaft bearing and a branch leading to said inlet chamber, individual oil How control means in each branch, all said moving parts having plane ends terminating in the same planes and having peri heral and end surfaces smooth and devoi of oil grooves, said housing having plane surfaces devoid of oil grooves, the clearances between said plane surfaces being so small that oil suflicient for mechanical lubrication as distinguished from a Hooded hydraulic seal, establishes a gas-tight capillary seal in addition to lubricating the parts.

3. A vacuum pump comprising a housing, a drive shaft in said housing, an eccentric cylinder on said drive shaft in said housing,

a blade-integral with said cylinder and eX-' tending upwardly therefrom, sealing segments journaled in said housing and lying on either side of said blade, said housing defining an inlet chamber above said sealing segments, an oil reservoir subjected to the pressure on the discharge side of said pump, a branched conduit from said reservoir having a branch leading to each shaft bearing and a branch leading to said inlet chamber, individual oil flow control means in the branch leading to said inlet chamber, all said moving parts having plane ends terminating in the same planes and having peripheral and end surfaces smooth and devoid of oil grooves, said housing having complementary plane surfaces also devoid of grooves.

4. A pump comprisin a housing, an eccentric cylinder in sai housing, the periphery of the cylinder being smooth and devoid of oil grooves, the ends of the cylinder each lying all in one plane and being smooth and devoid of oil grooves, said housing having complementary peripheral and end faces also smooth and devoid of oil grooves, and oil supply means for delivering oil to the parts, the clearances between the parts being such that the capilla oil film l necessary for mechanical lubricant has capillary strength in excess of the gaseous pressure differences generated by said pump, -wherby an effective capillary seal may be maintained at every. point without flooded lubrication.

5. A pump comprising a housing, an eccentric cylinder in said housing, the periphery of the cylinder being smooth and devoid of oil grooves, the ends of the cylinder each lying all in one plane and being smooth and devoid of oil grooves, said housing having complementary peripheral and end faces also smooth and devoid of oil grooves, and oil supply means for delivering independently controlled amounts of oil to the ends of the cylinder andl to the periphery thereof, said cylinder and housing having clearances such that the capillary fi m necessary for mechanical lubrication has capillary strength in excess of the gaseous pressure dierences generated by said pump, whereby an eifective capillary seal is maintained throughout, and hydraulic sealing by flooded lubrication is avoided.

In testimony whereof I hereunto aiiix my signature.

OLIVER S. SLEEPER. 

